Application of Differential Display RT‐PCR and EST/Microarray Technologies to the Analysis of Gene Expression in Response to Drought Stress and Elimination of Aflatoxin Contamination in Corn and Peanut

Aflatoxin contamination in the field is known to be influenced by numerous factors. Drought and high temperatures are conducive to Aspergillus flavus infection and aflatoxin contamination. This article will review the application of new molecular tools to study host resistance to biotic and abiotic factors affecting preharvest aflatoxin contamination in corn and peanut. We will also summarize recent studies conducted in our laboratories to evaluate the relationship of drought tolerance and aflatoxin contamination, and discuss the progress in using genetic engineering approaches to control preharvest aflatoxin contamination. The application of molecular tools, such as proteomics, DD‐RT‐PCR (differential display reverse transcription‐polymerase chain reaction), expressed sequence tag (EST) and gene chip technology (macro/micro‐array) to study gene expression in response to drought stress, and genetic transformation, will be reviewed. We have used DD‐RT‐PCR to display genes expressed in peanut and corn grown under drought stress vs irrigation condition. A new program has been initiated to use EST/microarray technology to study the whole genome as influenced by drought stress in corn and peanut. We are also studying A. flavus ESTs to better understand the genetic control and regulation of toxin biosynthesis. Because of the complexity of the Aspergillus‐plant (corn and peanut) interactions, better understanding of the genetic mechanisms of resistance will be needed using both conventional and molecular breeding for crop improvement and control of preharvest aflatoxin contamination. Genetic improvement of crop resistance to drought stress is one component and will provide a good perspective on the efficacy of control strategy through genetic improvement.